At the reunion dinner, let them know you want to plan the next reunion (i'm sure you've already done this). Already have the idea of where and when you want to have it.

As far as the places you named, i know nothing. But, you can always contact the cities visitor bureau, for example Chicago has one, and let them know you're planning a reunion for x # of people and need hotel and nice places to have it. Sometimes they will assist you in getting group rates for your family. http://www.choosechicago.com/Pages/default.aspx

Send out the family letter well in advance and gear it towards fun. if you plan this year and it turns to be a ball, more people will hear and want to come for the next ones.

Hope that helps.

~Allum
www.spence-lowry.blogspot.com